Expanding tool

ABSTRACT

A nonrigid portion is attached to the end of the tapered rigid mandrel of an epicyclic motion roller-type tube expander unit to enable tube bends to be located closer to the end fitting to which the tube is being attached.

ite States Patent Press Feb. 15, 1972 [54] EXPANDING TOOL [56]References Cited [72] Inventor: Irving D. Press, West Orange, NJ. UNITEDSTATES PATENTS [73] Assignee: Resistoflex Corporation, Roseland, NJ. 1,530,381 3/1925 Leedom ..72/123 [22] Filed: June I, 1970 PrimaryExaminer-Lowell A. Larson [21] APPL 41,808 Attorney-Robert M. Freeman[52] 11.8. Cl ..72/122, 72/120, 72/393 [57] ABSTRACT [51] Int. Cl...B2Id 39/06, B2ld 39/19 A nonrigid portion is attached to the and ofthe tapered rigid [58] FleldofSearch ..72/ll7,120, 122,123,393,

29/523 mandrel of an eplcycllc motion roller-type tube expander um! toenable tube bends to be located closer to the end fitting to which thetube is being attached.

3 Claims, 4 Drawing Figures EXPANDING TOOL The present invention relatesto a tool for expanding the inside diameter of the end of a metal tube,and more particularly, to a tool for accomplishing such expansion forthe purpose of attaching an end fitting to the tube end.

End fittings are known which have a bore enterable from one end by theend of a metal tube with a sliding fit where the bore is provided with aplurality of axially spaced circumferential grooves into which the metalof the tube is caused to flow by radial expansion of the inside diameterof the tube. Heretofore, a tool has been used for accomplishing theassembly mentioned previously. Such tool includes a fixture die forsurrounding and backing up the fitting and an expander unit. Theexpander unit has a plurality of rollers spaced circumferentially aroundits longitudinal axis and located within the confines of individualslots in a tubular cage with the axes of the rollers skewed slightlyrelative to the axis of the expander unit. The rollers are radiallyprojected by interaction with the tapered surface of a rotatable hardmetal mandrel when the latter translates axially relative to and betweenthe rollers. Rotation of the mandrel imparts epicyclic motion to therollers when they are in contact with a tube wall. The slots whichconfine the rollers have tapered sidewalls permitting the rollers tofall inwardly if otherwise unrestrained but preventing radially outwardseparation of the rollers from the cage. To prevent radially inwardseparation the mandrel is constrained to remain between the rollers atall times. However, because the rollers are adjacent an end of thetubular cage, the mandrel projects axially a substantial distancetherefrom when the mandrel is fully advanced within the expander. Aswill be explained more fully hereinafter, the projection of the mandrelhas placed a limitation on the proximity of a bend in the tubing as itleaves the end fitting.

With the foregoing in mind, it is an object of the present invention toprovide an improved expander of the foregoing type which substantiallyeliminates the aforementioned limitation on proximity ofa bend to theend fitting.

In accordance with the invention the end of the mandrel which remainsbetween the rollers when the mandrel is fully retracted is made nonrigidwhile the remainder of the mandrel is rigid.

The invention will be better understood after reading the followingdetailed description of the presently preferred embodiment thereof withreference to the appended drawings in which:

FIG. 1 is an elevational view partly in section showing a typicalassembly of an end fitting and a metal tube with a bend adjacent thefitting;

FIG. 2 is a longitudinal sectional view through the tool fixture andexpander in association with the assembly of FIG. 1 at thecompletion ofthe expanding operation;

FIG. 3 is a longitudinal sectional view through an expander unitconstructed in accordance with the present invention; and

FIG. 4 is a view similar to FIG. 2 showing the use of the tool of FIG.3.

The same reference numerals are used throughout the drawings todesignate the same or similar parts.

Referring now to FIG. 1, there is shown a typical assembly consisting ofan end fitting l and a section of metal tubing 11 wherein the tubing issecured to the fitting by radially ex panding the inner surface 12 todisplace metal into the axially spaced circumferential grooves 13. Thearrow 14 designates the distance from the end 15 of the fitting 10 tothe inner surface of the bend in the tube 11 as measured along thelongitudinal axis 16 of the fitting. Heretofore, it has not beenpossible to reduce the distance 14 below a limiting minimum because ofthe nature of the expander tool as seen in FIG. 2 to which attention isnow directed.

As shown in FIG. 2, the assembly of FIG. 1 is located within the fixturedie 17, normally formed in two halves and held together by a die cagering 18 and lock screw 19. The enclosure 20 for the expander toolbearing is secured by an interlocking groove and flange arrangementwithin the fixture 17.

The expander unit includes a plurality of rollers of which two, 21 and22, are seen in FIG. 2, spaced circumferentially around the longitudinalaxis of the unit located within the confines of individual slots in thetubular cage 23. The axes of the rollers are skewed slightly relative tothe axis of the expander unit. The mandrel 24 has one end provided withthe wrench flats at 25 and the other end at 26 provided with a reduceddiameter portion for retaining the rollers when the mandrel is fullyretracted. As shown in FIG. 2, the mandrel is in its fully forwardposition. The fully forward position may be regulated by adjustment ofthe stop sleeve or collar 27 which is locked in place by a lock nut 28.The stop sleeve 27 and lock nut 28 are mounted on a tubular guide 29through which the mandrel passes. The guide 29 is journaled in theenclosure 20. FIG. 2 shows the expander unit in the fully forwardposition after completion of an expanding operation. At the beginning ofthe operation the mandrel would be fully retracted to the right asviewed in the drawing. In order to accomplish the expanding operation awrench is applied to the flats 25 and the mandrel is rotated in aclockwise direction as viewed from the wrenching end. As the mandrel isrotated, it imparts epicyclic motion to the rollers 21 and 22 which, inturn, tend to feed the tapered mandrel axially forward toward theposition shown in FIGS. 2. The forward end of the tapered section of themandrel is shown just protruding at 30 from the end of the cage member23. It should, therefore, be apparent that the bend in the tube 1 1cannot be located any closer to the fitting than that shown in FIG. 2due to the projection of the end 26 of the mandrel 24. Unfortunately,this places an objectionable limitation upon the usefulness of this typeof assembly.

Referring now to FIG. 3, there is shown in greater detail theconstruction of the expander unit as modified in accordance with thepresent invention. The mandrel 24 has a central collar or shoulder 31which cooperates with the balls 32 and 33 to prevent further retractionof the mandrel beyond the position shown in FIG. 3. The end of themandrel at 34 is provided with a gradual taper which cooperates with therollers such as 22 to cause radially outward projection thereof as themandrel advances longitudinally. The cage 23 is provided with a flange35 which cooperates with the thrust bearings 36 and 37 within theenclosure 20. In order to prevent the rollers from moving radiallyinwardly so as to fall out of the cage 23 a length of head chain 38 isjoined to the end 39 of the mandrel 24. The length of the bead chainsection 38 is just sufficient to extend to the far end of the rollers.

Now referring to FIG. 4, the advantage achieved by use of the expanderunit of FIG. 3 will be readily apparent. As seen therein, the mandrel 24is in its fully forward position with the bead chain 38 pushed outbeyond the cage 23 and depending limply from the end 30 of the mandrel.Thus, the bend 40 in the tube 41 can be located right up against the endof the fitting being limited only by the clearance required for thefixture dies 17.

While a length of bead chain is shown in FIGS. 3 and 4, it will beunderstood that any nonrigid flexible strand or comparable element maybe joined to the end of the rigid mandrel section and provide thenecessary retention of the rollers when the mandrel is fully retracted.Wlth the smaller diameter expander units, it may be found that a lengthof wire is preferable in view of the difficulty in obtaining a beadchain of sufficiently small bead diameter. Any convenient method may beemployed for attaching the nonrigid portion to the rigid portion of themandrel.

Having described the presently preferred embodiment of the invention, itwill be understood by those skilled in the art that various changes inconstruction may be made without departing from the true spirit of theinvention as defined in the appended claims.

What is claimed is:

1. A tool for expanding the inside diameter of the end of a tube whereina plurality of rollers, which are circumferentially spaced around thelongitudinal axes of the tool within the confines of slots in a tubularcage with the axes of the rollers nonrigid while the remainder of themandrel is rigid.

2. A tool according to claim 1, wherein said nonrigid end of the mandrelcomprises a length of head chain attached to the adjacent end of therigid remainder of the mandrel.

3. A tool according to claim I, wherein said nonrigid end of the mandrelcomprises a flexible strand extending from the adjacent end of the rigidremainder of the mandrel.

1. A tool for expanding the inside diameter of the end of a tube whereina plurality of rollers, which are circumferentially spaced around thelongitudinal axes of the tool within the confines of slots in a tubularcage with the axes of the rollers skewed slightly relative to the toolaxes, are radially projected by interaction with the tapered surface ofa rotatable mandrel when the latter translates axially relative to andbetween the rollers, and wherein rotation of the mandrel impartsepicyclic motion to the rollers when in contact with a tube wall;characterized in that the end of the mandrel which remains between therollers to prevent them from falling radially inwardly out of the slotsin the cage when the mandrel is fully retracted is nonrigid while theremainder of the mandrel is rigid.
 2. A tool according to claim 1,wherein said nonrigid end of the mandrel comprises a length of beadchain attached to the adjacent end of the rigid remainder of themandrel.
 3. A tool according to claim 1, wherein said nonrigid end ofthe mandrel comprises a flexible strand extending from the adjacent endof the rigid remainder of the mandrel.